1. Field of the Invention
The present invention relates to mechanisms for rotationally moving an object. More specially, the present invention relates to a mechanism for rotationally moving a mirror for effecting the scanning of a slit of light across a patient""s cornea.
2. Description of Related Art
In certain applications it is important to control the angular position of a rotating element with high accuracy and precision. For example, in ophthalmic diagnostic equipment such as a corneal topographer, it is necessary to rotate or scan a light slit across the cornea of the eye. For example, the ORBSCAN(trademark) Corneal Topographer available from Bausch and Lomb Incorporated scans a slit of light across the cornea of a patient""s eye.
Typically in the prior art, such devices as Galvanometers have provided precision angular position detection in order to provide a discreet and accurate rotation of such devices as mirrors. Galvanometers typically achieve their accuracy using variable-inductance transducers or variable-capacitance transducers. These Galvanometers typically depend on change in inductance or capacitance in the angular position of a rotor of an electrical motor to determine the position of the rotor. While these Galvanometer rotating systems are highly accurate, they are also costly and their size can be of concern, especially in ophthalmic applications where smaller size allows easy measurement of an eye.
Therefore, it would advantageous to have a mechanism to rotationally move a mirror in order to scan light, especially a slit of light across the cornea of an eye using a compact and cost effective design.